Nowadays, the Electric Arc Furnaces (EAF) are the most frequently used method for the steel production. With such method there are however problems related to energy consumption, thermal losses, electrode consumption, maintenance costs, quality of the steel obtained in this way and, last but not least, the environmental situation for the workers.
Till now the steel plants management has tried to increase the EAF capacity in order to increase the quantity of the produced steel and consequently to reduce the unit cost, dividing the total cost on a larger quantity of produced material.
The electric steel industry demand is a technology to improve the product quality and to reach higher productivity, also considering:
lower costs and consumption for the electric energy; PA1 lower electrode consumption; PA1 lower maintenance requirements, i.e. higher availability production time; PA1 max. flexibility in the utilisation of alternative power sources as gas, carbon, post-combustion energy, etc; PA1 max. utilisation of the off-gases to pre-heat the scrap to be melted; PA1 environmental situation improvement for the steel-making facility in respect to noise, off-gases volume, amount of dust, etc; PA1 reduction of the flicker in connection with higher productivity; PA1 possibility to retrofit in the existing steel plants. PA1 the capacity of the different vessels increases starting from the first one, and PA1 the row material (scrap) to be cast is divided into a charge for the first vessel and a second charge for the at least second vessel of the furnace; PA1 the charge of the first vessel of the furnace is melted using electric energy and alternative combustion energy; PA1 the off-gases from the first vessel can be conveyed to the second vessel of the furnace in order to pre-heat the scrap present in the second vessel, and the off-gases of the second vessel, in different time, can reach the first vessel to pre-heat the present scrap; PA1 the molten steel of the first vessel is poured in the second (at least) vessel to contribute, with its thermal energy, to cast the scrap present in the second vessel; PA1 the melted metal of the second vessel of the furnace is discharged for the use.
One part of these requirements are already fulfilled by the several developments in the last years, but always with certain compromises without complete answers to all demands.